Curtain Size Calculator
Calculate the exact width and height for each curtain panel to achieve the perfect fit and fullness for your windows.
How Curtain Size Calculator Works
Getting the right curtain size involves more than just measuring your window. You need to account for the desired fullness (how gathered the fabric looks when closed) and the curtain type (which affects the final length).
The calculator determines the width of each panel by taking your window width, multiplying it by your chosen fullness factor (1.5x for standard, 2x for deluxe, or 2.5x for ultra), then dividing by two since most curtains come as a pair.
For height, it adds extra length based on your curtain type: 15 inches for standard sill/apron/floor length (for rod placement and slight pooling), half the window height for café curtains (which only cover the bottom portion), or 30 inches for extra-long curtains (for dramatic pooling or very high rod placement).
This approach ensures your curtains will hang properly with the right amount of fabric to create the look you want, whether that's a sleek tailored appearance or luxurious gathered folds.
Curtain Size Calculator Formula Breakdown
Formula
Curtain Panel Width = (Window Width × Fullness Factor) ÷ 2
Curtain Panel Height = Window Height + Extra Length (based on curtain type)Variables Explained
- Curtain TypeThe style and length of curtains you want. Sill/apron/floor length are standard curtains that end at the window sill, apron, or floor. Café curtains cover only the bottom half of the window. Extra long curtains are designed for dramatic pooling on the floor or very high rod placement.
- Curtain FullnessHow gathered or full you want the curtains to look when closed. Standard fullness (1.5x) creates a tailored look, deluxe fullness (2x) provides nice folds and is most popular, while ultra fullness (2.5x) creates luxurious, dramatic gathers.
- Window HeightThe vertical measurement from the top of your window to where you want the curtains to end. Measure from the window frame top to the sill, apron, or floor depending on your desired curtain length.
- Window WidthThe horizontal measurement across your window from the outer left edge to the outer right edge of the window frame. This is your starting point for calculating how much fabric width you need.
Example Calculation
Given:
- Curtain Type: Sill, apron or floor length
- Curtain Fullness: Deluxe fullness (2x)
- Window Height: 20 inches
- Window Width: 30 inches
Calculation:
Total curtain width needed: 30 inches × 2 (deluxe fullness) = 60 inches
Width per panel: 60 inches ÷ 2 panels = 30.00 inches
Panel height: 20 inches + 15 inches (extra for rod and pooling) = 35.00 inchesResult:
Each curtain panel should be 30.00 inches wide and 35.00 inches tallExplanation
This example shows curtain sizing for a standard bedroom window. The deluxe fullness creates attractive folds when the curtains are closed, while the extra 15 inches in height allows for proper rod placement and a slight puddle on the floor for an elegant look.
Tips for Using Curtain Size Calculator
- 💡Always measure your window multiple times and use the largest measurement to ensure proper coverage, especially for windows that aren't perfectly square.
- 💡Consider your fabric choice when selecting fullness - heavier fabrics like velvet look great with standard fullness, while lighter fabrics like linen benefit from deluxe or ultra fullness.
- 💡If you're unsure about curtain length, err on the side of longer rather than shorter - you can always hem curtains, but you can't add length.
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